The present disclosure relates generally to optical devices, and more specifically to optical devices including a repositionable mirror and an optical sensor.
With recent advances in technology, there is an increasing interest in the use of free-space optical (FSO) communications for various applications. Compared to other communications technologies, a FSO communications link can have advantages of higher mobility and compact size, better directionality (e.g., harder to intercept), faster set up and tear down, and/or suitability for situations where one or both transceivers are moving. Thus, FSO communications links can be used in many different scenarios, including in airborne, sea-based, space and/or terrestrial situations.
FSO transceivers generally need to be aligned with each other to exchange data owing to the narrow beam spread of their operating wavelengths. For example, a FSO transceiver operating at a wavelength of 1550 nm has a beam spread of approximately 0.01 degrees or less. When communicating over long distances in free space, for example on the order of 10 kilometers, accurate pointing is essential as the slightest misalignment can result in one transceiver not being able to receive the other's signal. Further, if the transceivers are mounted on a moving platform such as a communications tower, the tower can sway due to wind or other natural causes. Physical alignment of the transceiver can only partially address this issue. As a result, FSO communications systems have need for real-time beam steering systems that respond to rapid (as high as a few hundred hertz) change in the position of the transceiver or in the position of a received beam so that a transceiver can continue to communicate with a remote transceiver. However, depending upon their implementation, real time positioning sensors can have drawbacks that affect the performance of the transceiver.
The figures depict various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein.